The O-methylated flavonoids or methoxyflavonoids are

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

s with

methylation In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These t ...

s on

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

groups (

methoxy In organic chemistry, a methoxy group is the functional group consisting of a methyl group bound to oxygen. This alkoxy group has the formula . On a benzene ring, the Hammett equation classifies a methoxy substituent at the ''para'' position as ...

bonds). O-methylation has an effect on the solubility of flavonoids.

Enzymes

O-methylated flavonoids formation implies the presence of specific

O-methyltransferase An O-methyltransferase (OMT) is a type of methyltransferase enzyme transferring a methyl group on a molecule. Examples are : * Acetylserotonin O-methyltransferase * Apigenin 4'-O-methyltransferase * Caffeate O-methyltransferase * Caffeoyl-CoA ...

(OMT) enzymes which accept a variety of substrates. Those enzymes mediate the O-methylation on a specific hydroxyl group, like on 4' (example in ''

Catharanthus roseus ''Catharanthus roseus'', commonly known as bright eyes, Cape periwinkle, graveyard plant, Madagascar periwinkle, old maid, pink periwinkle, rose periwinkle, is a species of flowering plant in the family Apocynaceae. It is native and endemic to M ...

'') or 3' (example in rice) positions. Those positions can be ortho, meta, para and there can be a special 3-O-methyltransferase for the 3-OH position. Calamondin orange ('' Citrus mitis'') exhibits all of those activities.

Plant enzymes

Apigenin 4'-O-methyltransferase In enzymology, an apigenin 4'-O-methyltransferase () is an enzyme that catalyzes the chemical reaction :S-adenosyl-L-methionine + 5,7,4'-trihydroxyflavone \rightleftharpoons S-adenosyl-L-homocysteine + 4'-methoxy-5,7-dihydroxyflavone Thus, the t ...

* 8-hydroxyquercetin 8-O-methyltransferase * Isoflavone 4'-O-methyltransferase * Isoflavone 7-O-methyltransferase * Isoliquiritigenin 2'-O-methyltransferase *

Isoorientin 3'-O-methyltransferase In enzymology, an isoorientin 3'-O-methyltransferase () is an enzyme that catalyzes the chemical reaction :S-adenosyl-L-methionine + isoorientin \rightleftharpoons S-adenosyl-L-homocysteine + isoscoparin Thus, the two substrates of this enzyme ...

* Kaempferol 4'-O-methyltransferase * Luteolin O-methyltransferase * Methylquercetagetin 6-O-methyltransferase *

3-methylquercetin 7-O-methyltransferase In enzymology, a 3-methylquercetin 7-O-methyltransferase () is an enzyme that catalyzes the chemical reaction :S-adenosyl-L-methionine + 5,7,3',4'-tetrahydroxy-3-methoxyflavone \rightleftharpoons S-adenosyl-L-homocysteine + 5,3',4'-trihydroxy-3,7 ...

Myricetin O-methyltransferase In enzymology, a myricetin O-methyltransferase () is an enzyme that catalyzes the chemical reaction :2 S-adenosyl-L-methionine + myricetin \rightleftharpoons 2 S-adenosyl-L-homocysteine + syringetin Thus, the two substrates of this enzyme are S ...

* Quercetin 3-O-methyltransferase *

Vitexin 2"-O-rhamnoside 7-O-methyltransferase In enzymology, a vitexin 2"-O-rhamnoside 7-O-methyltransferase () is an enzyme that catalyzes the chemical reaction :S-adenosyl-L-methionine + vitexin 2"-O-beta-L-rhamnoside \rightleftharpoons S-adenosyl-L-homocysteine + 7-O-methylvitexin 2"-O-be ...

Animal enzyme

Catechol-O-methyl transferase Catechol-''O''-methyltransferase (COMT; ) is one of several enzymes that degrade catecholamines (neurotransmitters such as dopamine, epinephrine, and norepinephrine), catecholestrogens, and various drugs and substances having a catechol structu ...

O-methylated anthocyanidins

* 5-Desoxy-malvidin *

Capensinidin Capensinidin (Cp) is an O-methylated anthocyanidin. It is a water-soluble, blue-red plant dye. It is a 5-methoxy analog of malvidin, has been obtained from ''Plumbago capensis ''Plumbago auriculata'', the cape leadwort, blue plumbago or Cape p ...

Europinidin Europinidin (Eu) is an O-methylated anthocyanidin. It is a water-soluble, bluish red plant dye. It is a rare O-methylated flavonoid, a derivative of delphinidin. It can be found in some species of ''Plumbago ''Plumbago'' is a genus of 10–20 ...

Hirsutidin Hirsutidin is an O-methylated anthocyanidin, a chemical compound belonging to the anthocyanins. It can be found in ''Catharanthus roseus'' (Madagascar periwinkle) where it is the prominent compound in petals and can also be found in callus A ...

Malvidin Malvidin is an O-methylated anthocyanidin, the 3',5'-methoxy derivative of delphinidin. As a primary plant pigment, its glycosides are highly abundant in nature. Natural occurrences Malvidin is responsible for the blue color found in petals of ...

Peonidin Peonidin is an O-methylated anthocyanidin derived from Cyanidin, and a primary plant pigment. Peonidin gives purplish-red hues to flowers such as the peony, from which it takes its name, and roses. It is also present in some blue flowers, such as ...

Petunidin Petunidin (Pt), like Europinidin and Malvidin, is derived from Delphinidin and is an O-methylated anthocyanidin of the 3-hydroxy type. It is a natural organic compound, a dark-red or purple water-soluble pigment found in many redberries including ...

Pulchellidin Pulchellidin (Pl) is an ''O''-methylated anthocyanidin. It is a blue-red plant pigment. It can be found in ''Plumbago pulchella''. Glycosides * Pulchellidin 3-rhamnoside (molecular formula : C22H23O11, exact mass : 463.124036578) is reported in ' ...

* Rosinidin *

O-methylated flavanols

* Meciadanol (3-O'methyl catechin)

O-methylated flavanones

Hesperetin Hesperetin is the 4'-methoxy derivative of eriodictyol, a flavanone. Hesperetin's 7-O-glycoside, hesperidin, is a naturally occurring flavanon-glycoside, the main flavonoid in lemons and sweet oranges. Hesperetin (and naringenin, the parent flavan ...

Homoeriodictyol Homoeriodictyol is a bitter-masking flavanone extracted from Yerba Santa (''Eriodictyon californicum'') a plant growing in America. Homoeriodictyol (3`-methoxy-4`,5,7-trihydroxyflavanone) is one of the 4 flavanones identified by Symrise in this ...

Isosakuranetin Isosakuranetin, an O-methylated flavonoid, is the 4'-methoxy derivative of naringenin, a flavanone. Didymin, a disaccharide of isosakuranetin, occur e.g. in sweet orange, blood orange and mandarin. Isosakuranetin is a potent inhibitor of TRPM3 ch ...

Sakuranetin Sakuranetin is a flavan-on, the 7-methoxy derivative of naringenin, found in Polymnia fruticosa and rice, where it acts as a phytoalexin against spore germination of '' Pyricularia oryzae''. Glycosides Sakuranin is the 5-O- glucoside of sakura ...

* Sterubin

O-methylated flavanonols

* Dihydrokaempferide

''O''-methylated flavonols

of kaempferol *

Kaempferide Kaempferide is an ''O''-methylated flavonol, a type of chemical compound. It can be found in ''Kaempferia galanga'' (aromatic ginger). It has been noted to inhibit pancreatic cancer growth by blockading an EGFR-related pathway. Metabolism Th ...

of myricetin * Annulatin * Combretol * Europetin * Laricitrin (3'-O-Dimethylmyricetin) * 5-O-methylmyricetin * Syringetin (3',5'-O-Dimethylmyricetin) of quercetin *

Ayanin Ayanin is an ''O''-methylated flavonol, a type of flavonoid. It is the 3,7,4'-tri-''O''-methylated derivative of quercetin. It can be found in ''Croton schiedeanus''. It can also be synthetized. Biosynthesis The enzyme 3,7-dimethylquercetin 4 ...

Azaleatin Azaleatin is a chemical compound. It is an O-methylated flavonol, a type of flavonoid. It was first isolated from the flowers of ''Rhododendron mucronatum'' in 1956 and has since been recorded in forty-four other Rhododendron species, in ''Plumbago ...

Isorhamnetin Isorhamnetin is an O-methylated flavon-ol from the class of flavonoids. A common food source of this 3'-methoxylated derivative of quercetin and its glucoside conjugates are pungent yellow or red onions, in which it is a minor pigment, quercetin ...

Ombuin Ombuin is an O-methylated flavonol, a type of flavonoid. It is the 4',7-O-methyl derivative of quercetin. Ombuin can be found in species of the genus ''Erythroxylum''. It can also be synthesized. Ombuin 3-sulfate can be isolated from '' Flaveri ...

Pachypodol Pachypodol is an O-methylated flavonol, a type of chemical compound. It can be isolated from '' Pachypodanthium confine'', from leaves of ''Agastache rugosa, (Korean mint)'', Latin denomination of part of plant : Agastache folium ''Agastache'' ...

* Retusin (quercetin-3,7,3',4'-tetramethyl ether) *

Rhamnazin Rhamnazin is an ''O''-methylated flavonol, a type of chemical compound. It can be found in ''Rhamnus petiolaris'', a buckthorn plant endemic to Sri Lanka. Metabolism The enzyme 3-methylquercetin 7-''O''-methyltransferase uses ''S''-adenosyl m ...

Rhamnetin Rhamnetin is an O-methylated flavonol, a type of chemical compound. It can be isolated from cloves. The structure of the molecule was discovered by Austrian chemist Josef Herzig (1853–1924). Glycosides Rhamnetin is the aglycone of xanthorha ...

Tamarixetin Tamarixetin is an O-methylated flav-on-ol, a naturally occurring flavonoid. See also * Isorhamnetin, the 3'-methyl analog * List of antioxidants in food * List of phytochemicals in food While there is ample evidence to indicate the health b ...

other *

Eupatolitin Eupatolitin is a chemical compound. It is an ''O''-methylated flavonol, a type of flavonoid. Eupatolitin can be found in '' Brickellia veronicaefolia'' and in '' Ipomopsis aggregata''. Glycoside Eupatolin is a eupatolitin glycoside containing ...

Natsudaidain Natsudaidain is an O-methylated flavonol, a type of chemical compound. It can be isolated from Citrus plants (Rutaceae). The name of the molecule comes from ''Citrus natsudaidai'' (Natsumikan, lit. "summer tangerine"), a fruit of Japan developed in ...

O-methylated flavones

Acacetin Acacetin is a 4′- ''O''-methylated flavone of the parent compound apigenin, found in ''Robinia pseudoacacia ''Robinia pseudoacacia'', commonly known in its native territory as black locust, is a medium-sized hardwood deciduous tree, belon ...

Chrysoeriol Chrysoeriol is a flavone, chemically the 3'-methoxy derivative of luteolin. Related compounds Diosmetin is one of three possible regioisomer In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a compo ...

Diosmetin Diosmetin, also known as 5,7,3′-trihydroxy-4′-methoxyflavone, is an ''O''-methylated flavone, a chemical compound that can be found in the Caucasian vetch. It has been found to act as a weak TrkB receptor agonist. Glycosides Diosmetin is t ...

* Nepetin * Nobiletin *

Oroxylin-A Oroxylin A is an O-methylated flavone, a chemical compound that can be found in the medicinal plants ''Scutellaria baicalensis'' and ''Scutellaria lateriflora'', and the ''Oroxylum indicum'' tree. It has demonstrated activity as a dopamine reuptak ...

* Sinensetin *

Tangeritin Tangeretin is an O- polymethoxylated flavone that is found in tangerine and other citrus ''Citrus'' is a genus of flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops ...

* Thevetiaflavone *

Wogonin Wogonin is an O-methylated flavone, a flavonoid-like chemical compound which is found in ''Scutellaria baicalensis''. The glycosides of wogonin are known as wogonosides. For example, oroxindin is a wogonin glucuronide isolated from '' Oroxylum ...

O-methylated isoflavones

Biochanin A Biochanin A is an ''O''-methylated isoflavone. It is a natural organic compound in the class of phytochemicals known as flavonoids. Biochanin A can be found in red clover in soy, in alfalfa sprouts, in peanuts, in chickpea (''Cicer arietinum'' ...

Calycosin Calycosin is an ''O''-methylated isoflavone. It can be isolated from ''Astragalus membranaceus'' Bge. var. ''mongholicus'' and ''Trifolium pratense'' L. (red clover). Biosynthesis Isoflavone 3′-hydroxylase uses formononetin Formononetin is ...

Formononetin Formononetin is an O-methylated isoflavone. Natural occurrences Formononetin is found in a number of plants and herbs such as red clover. Along with other phytoestrogens, it predominantly occurs in leguminous plants and Fabaceae, particularly i ...

Glycitein Glycitein is an O-methylated isoflavone which accounts for 5-10% of the total isoflavones in soy food products. Glycitein is a phytoestrogen A phytoestrogen is a plant-derived xenoestrogen (see estrogen) not generated within the endocrine sy ...

Irigenin Irigenin is an O-methylated isoflavone, a type of flavonoid. It can be isolated from the rhizomes of the leopard lily ('' Belamcanda chinensis''), and ''Iris kemaonensis''. Jiaju Zhou, Guirong Xie and Xinjian Yan Glycosides Iridin is the 7-gl ...

* 5-O-methylgenistein * Pratensein *

Prunetin Prunetin is an O-methylated isoflavone, a type of flavonoid. It has been isolated for the first time by Finnemore in 1910 in the bark of ''Prunus emarginata'' (the Oregon cherry). Prunetin isolated from pea The pea is most commonly the sma ...

* Psi-tectorigenin * Retusin *

Tectorigenin Tectorigenin is an O-methylated isoflavone, a type of flavonoid. It can be isolated from leopard lily (''Belamcanda chinensis''), in ''Iris unguicularis'' or '' Pueraria thunbergiana''. Glycosides Tectoridin Tectoridin is an isoflavone Isofla ...

References

{{DEFAULTSORT:O-Methylated Flavonoid O-methylation